The metacommunity concept provides a theoretical framework that aims at explaining organism distributions by a combination of environmental filtering, dispersal, and drift. However, few works have attempted a multitaxon approach and even fewer have compared two distant biogeographical regions using the same methodology. We tested the expectation that temperate (mediterranean-climate) pond metacommunities would be more influenced by environmental and spatial processes than tropical ones, because of stronger environmental gradients and a greater isolation of waterbodies. However, the pattern should be different among groups of organisms depending on their dispersal abilities. We surveyed 30 tropical and 32 mediterranean temporary ponds from Costa Rica and Spain, respectively, and obtained data on 49 environmental variables. We characterized the biological communities of bacteria and archaea (from the water column and the sediments), phytoplankton, zooplankton, benthic invertebrates, amphibians and birds, and estimated the relative role of space and environment on metacommunity organization for each group and region, by means of variation partitioning using generalized additive models. Purely environmental effects were important in both tropical and mediterranean ponds, but stronger in the latter, probably due to their larger limnological heterogeneity. Spatially correlated environment and pure spatial effects were greater in the tropics, related to higher climatic heterogeneity and dispersal processes (e.g., restriction, surplus) acting at different scales. The variability between taxonomic groups in the contribution of spatial and environmental factors to metacommunity variation was very wide, but higher in active, compared with passive, dispersers. Higher environmental effects were observed in mediterranean passive dispersers, and higher spatial effects in tropical passive dispersers. The unexplained variation was larger in the tropical setting, suggesting a higher role for stochastic processes, unmeasured environmental factors, or biotic interactions in the tropics, although this difference affected some actively dispersing groups (insects and birds) more than passive dispersers. These results, despite our limitations in comparing only two regions, provide support, for a wide variety of aquatic organisms, for the classic view of stronger abiotic niche constraints in temperate areas compared with the tropics. The heterogeneous response of taxonomic groups between regions also points to a stronger influence of regional context than organism adaptations on metacommunity organization.

中文翻译：

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分类群对地中海和热带池塘元群落空间和环境的不一致反应

元社区概念提供了一个理论框架，旨在通过环境过滤、扩散和漂移的组合来解释生物分布。然而，很少有作品尝试过多分类方法，更少有作品使用相同的方法比较两个遥远的生物地理区域。我们测试了温带（地中海气候）池塘元群落比热带池塘元群落受环境和空间过程影响更大的预期，因为环境梯度更强，水体隔离度更高。然而，根据它们的传播能力，不同生物群之间的模式应该是不同的。我们分别调查了来自哥斯达黎加和西班牙的 30 个热带和 32 个地中海临时池塘，并获得了 49 个环境变量的数据。我们对细菌和古细菌（来自水柱和沉积物）、浮游植物、浮游动物、底栖无脊椎动物、两栖动物和鸟类的生物群落进行了表征，并评估了空间和环境对每个群体和区域的元群落组织的相对作用，方法是使用广义加性模型的变异划分。纯粹的环境影响在热带和地中海池塘中都很重要，但在后者中更强，可能是由于它们更大的湖沼异质性。热带地区的空间相关环境和纯空间效应更大，与更高的气候异质性和扩散过程（例如，限制、过剩）在不同尺度上起作用有关。空间和环境因素对元群落变异的贡献在分类群之间的变异性非常大，但与被动传播者相比，主动传播者更高。在地中海被动扩散器中观察到更高的环境影响，在热带被动扩散器中观察到更高的空间影响。无法解释的变化在热带环境中更大，表明随机过程、未测量的环境因素或热带生物相互作用的作用更大，尽管这种差异对一些主动传播群体（昆虫和鸟类）的影响大于被动传播者。尽管我们仅比较两个区域存在局限性，但这些结果为多种水生生物提供了支持，与热带相比，温带地区的非生物生态位限制更强的经典观点。区域间分类群的异质性反应也表明区域背景对元群落组织的影响比生物体适应性更强。